This invention relates to a fuel system, and more particularly, the invention relates to a fuel system to be used for industrial gas turbine engines utilizing water to reduce nitrous oxide emissions.
Many current industrial gas turbine engines require that water be injected into the combustor along with the liquid or gaseous fuel in order to reduce levels of nitrous oxide (NOX) emissions. Current systems have simply adapted conventional systems that utilize fuel only. Typically, the conventional fuel systems employ a pump and metering device that controls the volumetric flow rate of fuel delivered to the gas turbine engine. These systems have been modified to incorporate water injection by supplying a separate pump and metering device for the water supply portion of the fuel system.
Fuel systems utilizing water injection must thoroughly mix the water with the fuel prior to injection in to the combustor in order to yield the desired NOX reduction. Prior art systems have employed a mixing block having numerous screens to generate turbulent flow and create a vortex in an effort to homogeneously mix the fuel and water. However, the fuel and water is not typically sufficiently mixed to provide the optimal NOX reduction. Furthermore, these adapted fuel systems are overly complex, costly and require significant floor space around the engine because they employ redundant components. That is, separate pumps, metering devices, and other valves and flow meters are needed for each of the water and fuel supplies. Therefore, what is needed is a simplified fuel system capable of delivering a homogeneous mixture of fuel and water to the turbine engine.